Implanted medical devices, can receive programmed instructions, and can also send back messages regarding the status of the implantable medical device. This ability to interrogate with an implantable medical device in place in a patient is called telemetry. Telemetry can provide, among other things, useful information for troubleshooting implanted medical devices. Information sent from an external programmer to the implanted medical device can be used to program parameters for performing particular functions using the implanted device. The inductively coupled telemetry signal is generally quite local, to decrease the likelihood of inappropriate alteration of the program by environmental sources of radiofrequency energy or magnetic fields.
The evolution of biomedical telemetry has led to the development of increasingly sophisticated communication between implantable devices and external programmer that provides device's therapies or monitoring capabilities. Most of these external programmers rely on detachable coil assemblies ranging in size of about 2 to 3 inches in diameter to be optimally placed (e.g., at the site of device implantation, or in front of a patient at about 2 inches or less from the site of device implantation), for optimal signaling and inductive coupling between the implanted device and the external coil. These coil assemblies are connected to the external programmer unit to convey the signaling to and from the coils. Most existing external coil assemblies are hand-held types that must be kept stationary in this optimal position during an entire session of telemetry. During a typical telemetry session at a hospital or follow-up clinic, the patient or a medical care giver holds the coil in the optimum position.
With these telemetry communication devices, a coil-to-coil inductive coupling is usually used for wireless transmission of signals. Wireless signaling of implantable device telemetry enters through the coil via inductive coupling. The external coil is inductively coupled to a telemetry coil in the implanted device. The telemetry coil within the implantable device is usually fairly small and can usually only transmit small amounts of signal power to the exterior of a patient. Thus, an existing external coil assembly connected to a device programmer must be optimally placed for best signaling and inductive coupling to obtain a reliable telemetry communication. However, this reliance on optimal placement is generally undesirable because, the patient and/or care giver may find it tiring or difficult to find the optimal position and hold the external coil in place during the entire session. Increasing demands on the telemetry system to transmit and receive more data, may require long telemetry sessions. The medical care giver may require free movement of hands to perform other tasks. Moreover, requiring the coil to be positioned over the implanted medical device may, interfere with other medical procedures associated with the implanted device. Thus, there is a need for an improved biomedical telemetry apparatus to provide telemetry communication between the external programmer and the implanted medical device even when the external coil is not optimally placed. Also, there is a need for an improved biomedical telemetry apparatus to reduce or eliminate the need to hold the coil by hand in the optimal position during the telemetry sessions.